Fix profile update in duplicat_loop_body_to_header_edge for loops with 0 count_in
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Commit Message
Hi,
this patch makes duplicate_loop_body_to_header_edge to not drop profile counts to
uninitialized when count_in is 0. This happens because profile_probability in 0 count
is undefined.
Bootstrapped/regtested x86_64-linux, committed.
gcc/ChangeLog:
* cfgloopmanip.cc (duplicate_loop_body_to_header_edge): Special case loops with
0 iteration count.
@@ -1296,6 +1296,16 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e,
}
profile_probability prob_pass_wont_exit =
new_count_le.probability_in (count_in);
+ /* If profile count is 0, the probability will be uninitialized.
+ We can set probability to any initialized value to avoid
+ precision loss. If profile is sane, all counts will be 0 anyway. */
+ if (!count_in.nonzero_p ())
+ {
+ prob_pass_thru
+ = profile_probability::always ().apply_scale (1, 2);
+ prob_pass_wont_exit
+ = profile_probability::always ().apply_scale (1, 2);
+ }
scale_step = XNEWVEC (profile_probability, ndupl);
@@ -1306,7 +1316,9 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e,
/* Complete peeling is special as the probability of exit in last
copy becomes 1. */
- if (flags & DLTHE_FLAG_COMPLETTE_PEEL)
+ if (!count_in.nonzero_p ())
+ ;
+ else if (flags & DLTHE_FLAG_COMPLETTE_PEEL)
{
profile_count wanted_count = e->count ();